Commit 34d6b470 authored by Zach O'Keefe's avatar Zach O'Keefe Committed by Andrew Morton
Browse files

mm/khugepaged: add struct collapse_control 

Modularize hugepage collapse by introducing struct collapse_control.  This
structure serves to describe the properties of the requested collapse, as
well as serve as a local scratch pad to use during the collapse itself.

Start by moving global per-node khugepaged statistics into this new
structure.  Note that this structure is still statically allocated since
CONFIG_NODES_SHIFT might be arbitrary large, and stack-allocating a
MAX_NUMNODES-sized array could cause -Wframe-large-than= errors.

[zokeefe@google.com: use minimal bits to store num page < HPAGE_PMD_NR]
  Link: https://lkml.kernel.org/r/20220720140603.1958773-2-zokeefe@google.com
  Link: https://lore.kernel.org/linux-mm/Ys2CeIm%2FQmQwWh9a@google.com/
[sfr@canb.auug.org.au: fix build]
  Link: https://lkml.kernel.org/r/20220721195508.15f1e07a@canb.auug.org.au
[zokeefe@google.com: fix struct collapse_control load_node definition]
  Link: https://lore.kernel.org/linux-mm/202209021349.F73i5d6X-lkp@intel.com/
  Link: https://lkml.kernel.org/r/20220903021221.1130021-1-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-4-zokeefe@google.com


Signed-off-by: default avatarZach O'Keefe <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent c6a7f445

mm/khugepaged.c

+50 −37
Original line number Diff line number Diff line
@@ -85,6 +85,14 @@ static struct kmem_cache *mm_slot_cache __read_mostly; 


#define MAX_PTE_MAPPED_THP 8



struct collapse_control {

	/* Num pages scanned per node */

	u32 node_load[MAX_NUMNODES];



	/* Last target selected in khugepaged_find_target_node() */

	int last_target_node;

};



/**

 * struct mm_slot - hash lookup from mm to mm_slot

 * @hash: hash collision list
@@ -735,9 +743,12 @@ static void khugepaged_alloc_sleep(void) 
	remove_wait_queue(&khugepaged_wait, &wait);

}



static int khugepaged_node_load[MAX_NUMNODES];



static bool khugepaged_scan_abort(int nid)

struct collapse_control khugepaged_collapse_control = {

	.last_target_node = NUMA_NO_NODE,

};



static bool khugepaged_scan_abort(int nid, struct collapse_control *cc)

{

	int i;
@@ -749,11 +760,11 @@ static bool khugepaged_scan_abort(int nid) 
		return false;



	/* If there is a count for this node already, it must be acceptable */

	if (khugepaged_node_load[nid])

	if (cc->node_load[nid])

		return false;



	for (i = 0; i < MAX_NUMNODES; i++) {

		if (!khugepaged_node_load[i])

		if (!cc->node_load[i])

			continue;

		if (node_distance(nid, i) > node_reclaim_distance)

			return true;
@@ -772,32 +783,31 @@ static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void) 
}



#ifdef CONFIG_NUMA

static int khugepaged_find_target_node(void)

static int khugepaged_find_target_node(struct collapse_control *cc)

{

	static int last_khugepaged_target_node = NUMA_NO_NODE;

	int nid, target_node = 0, max_value = 0;



	/* find first node with max normal pages hit */

	for (nid = 0; nid < MAX_NUMNODES; nid++)

		if (khugepaged_node_load[nid] > max_value) {

			max_value = khugepaged_node_load[nid];

		if (cc->node_load[nid] > max_value) {

			max_value = cc->node_load[nid];

			target_node = nid;

		}



	/* do some balance if several nodes have the same hit record */

	if (target_node <= last_khugepaged_target_node)

		for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;

	if (target_node <= cc->last_target_node)

		for (nid = cc->last_target_node + 1; nid < MAX_NUMNODES;

		     nid++)

			if (max_value == khugepaged_node_load[nid]) {

			if (max_value == cc->node_load[nid]) {

				target_node = nid;

				break;

			}



	last_khugepaged_target_node = target_node;

	cc->last_target_node = target_node;

	return target_node;

}

#else

static int khugepaged_find_target_node(void)

static int khugepaged_find_target_node(struct collapse_control *cc)

{

	return 0;

}
@@ -1077,10 +1087,9 @@ static void collapse_huge_page(struct mm_struct *mm, 
	return;

}



static int khugepaged_scan_pmd(struct mm_struct *mm,

			       struct vm_area_struct *vma,

			       unsigned long address,

			       struct page **hpage)

static int khugepaged_scan_pmd(struct mm_struct *mm, struct vm_area_struct *vma,

			       unsigned long address, struct page **hpage,

			       struct collapse_control *cc)

{

	pmd_t *pmd;

	pte_t *pte, *_pte;
@@ -1100,7 +1109,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, 
		goto out;

	}



	memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));

	memset(cc->node_load, 0, sizeof(cc->node_load));

	pte = pte_offset_map_lock(mm, pmd, address, &ptl);

	for (_address = address, _pte = pte; _pte < pte + HPAGE_PMD_NR;

	     _pte++, _address += PAGE_SIZE) {
@@ -1166,16 +1175,16 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, 


		/*

		 * Record which node the original page is from and save this

		 * information to khugepaged_node_load[].

		 * information to cc->node_load[].

		 * Khugepaged will allocate hugepage from the node has the max

		 * hit record.

		 */

		node = page_to_nid(page);

		if (khugepaged_scan_abort(node)) {

		if (khugepaged_scan_abort(node, cc)) {

			result = SCAN_SCAN_ABORT;

			goto out_unmap;

		}

		khugepaged_node_load[node]++;

		cc->node_load[node]++;

		if (!PageLRU(page)) {

			result = SCAN_PAGE_LRU;

			goto out_unmap;
@@ -1226,7 +1235,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, 
out_unmap:

	pte_unmap_unlock(pte, ptl);

	if (ret) {

		node = khugepaged_find_target_node();

		node = khugepaged_find_target_node(cc);

		/* collapse_huge_page will return with the mmap_lock released */

		collapse_huge_page(mm, address, hpage, node,

				referenced, unmapped);
@@ -1881,8 +1890,9 @@ static void collapse_file(struct mm_struct *mm, 
	/* TODO: tracepoints */

}



static void khugepaged_scan_file(struct mm_struct *mm,

		struct file *file, pgoff_t start, struct page **hpage)

static void khugepaged_scan_file(struct mm_struct *mm, struct file *file,

				 pgoff_t start, struct page **hpage,

				 struct collapse_control *cc)

{

	struct page *page = NULL;

	struct address_space *mapping = file->f_mapping;
@@ -1893,7 +1903,7 @@ static void khugepaged_scan_file(struct mm_struct *mm, 


	present = 0;

	swap = 0;

	memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));

	memset(cc->node_load, 0, sizeof(cc->node_load));

	rcu_read_lock();

	xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) {

		if (xas_retry(&xas, page))
@@ -1918,11 +1928,11 @@ static void khugepaged_scan_file(struct mm_struct *mm, 
		}



		node = page_to_nid(page);

		if (khugepaged_scan_abort(node)) {

		if (khugepaged_scan_abort(node, cc)) {

			result = SCAN_SCAN_ABORT;

			break;

		}

		khugepaged_node_load[node]++;

		cc->node_load[node]++;



		if (!PageLRU(page)) {

			result = SCAN_PAGE_LRU;
@@ -1955,7 +1965,7 @@ static void khugepaged_scan_file(struct mm_struct *mm, 
			result = SCAN_EXCEED_NONE_PTE;

			count_vm_event(THP_SCAN_EXCEED_NONE_PTE);

		} else {

			node = khugepaged_find_target_node();

			node = khugepaged_find_target_node(cc);

			collapse_file(mm, file, start, hpage, node);

		}

	}
@@ -1963,8 +1973,9 @@ static void khugepaged_scan_file(struct mm_struct *mm, 
	/* TODO: tracepoints */

}

#else

static void khugepaged_scan_file(struct mm_struct *mm,

		struct file *file, pgoff_t start, struct page **hpage)

static void khugepaged_scan_file(struct mm_struct *mm, struct file *file,

				 pgoff_t start, struct page **hpage,

				 struct collapse_control *cc)

{

	BUILD_BUG();

}
@@ -1975,7 +1986,8 @@ static void khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot) 
#endif



static unsigned int khugepaged_scan_mm_slot(unsigned int pages,

					    struct page **hpage)

					    struct page **hpage,

					    struct collapse_control *cc)

	__releases(&khugepaged_mm_lock)

	__acquires(&khugepaged_mm_lock)

{
@@ -2047,12 +2059,13 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, 


				mmap_read_unlock(mm);

				ret = 1;

				khugepaged_scan_file(mm, file, pgoff, hpage);

				khugepaged_scan_file(mm, file, pgoff, hpage,

						     cc);

				fput(file);

			} else {

				ret = khugepaged_scan_pmd(mm, vma,

						khugepaged_scan.address,

						hpage);

						hpage, cc);

			}

			/* move to next address */

			khugepaged_scan.address += HPAGE_PMD_SIZE;
@@ -2108,7 +2121,7 @@ static int khugepaged_wait_event(void) 
		kthread_should_stop();

}



static void khugepaged_do_scan(void)

static void khugepaged_do_scan(struct collapse_control *cc)

{

	struct page *hpage = NULL;

	unsigned int progress = 0, pass_through_head = 0;
@@ -2129,7 +2142,7 @@ static void khugepaged_do_scan(void) 
		if (khugepaged_has_work() &&

		    pass_through_head < 2)

			progress += khugepaged_scan_mm_slot(pages - progress,

							    &hpage);

							    &hpage, cc);

		else

			progress = pages;

		spin_unlock(&khugepaged_mm_lock);
@@ -2185,7 +2198,7 @@ static int khugepaged(void *none) 
	set_user_nice(current, MAX_NICE);



	while (!kthread_should_stop()) {

		khugepaged_do_scan();

		khugepaged_do_scan(&khugepaged_collapse_control);

		khugepaged_wait_work();

	}